Toxic Effects of Nanoparticles on Fish Embryos

Nanoparticles are used widely in the in-drug delivery, diagnostics, cosmetics, paints, electronics, fabrics, solar cells, medicines etc. Their wide application is due to their special properties which include minute size, high reaction rate, increased surface area and quantum effect. Despite their multiple applications, nanoparticles have harmful effects too due to their improper disposal causing their entry into the aquatic environment greatly threatening the ecological security as well as our health. Zebra fishes (Danio rerio) are used more commonly for the evaluation of toxicity and are considered a promising animal model. Studies on Salmon and Labeo rohita have also been used for toxicity evaluation. Nanoparticles affect the embryo more easily than the adult since the embryo are more sensitive. Hence it becomes important for us to study the effect of the nanoparticles on the embryo of the fishes. These nanoparticles have the ability to cross the chorion layer and affect the developing embryo. Since the fishes are a part of the food chain, when these organisms get affected they will eventually harm the humans too. This review focuses on the effect of metal nanoparticles (NPs) like gold(Au), silver(Ag), copper(Cu), platinum and metal oxides nanoparticles like titanium dioxide, aluminium oxide, copper oxide, nickel oxide zinc oxide on the embryonic development of fish embryos. When compared to the other nanoparticles (NPs) like silver, copper and platinum, it has been observed that the gold nanoparticles (Au NPs) showed no toxicity to embryos of zebrafish though few studies contradict this. Aluminium nanoparticles showed no toxicity and role of reactive oxygen species (ROS) in enhancing the toxicity of nanoparticles have also been discussed.

Can Oryzias Celebensis Embryo be Transported Dry?

Embryos of the genus Oryzias have long been used as sentinel organisms in ecotoxicological research. Compared with animal models from mammals, Oryzias embryo offers several advantages such as being cost-effective, more sensitive, rapid and produce very little waste. In ecotoxicological studies, it is necessary to have inter-laboratory calibration on used techniques between one laboratory and another, so that the used techniques are reliable. Inter-laboratory calibration between laboratories requires transferring embryos from one laboratory to another. For this purpose, research has been carried out to compare the survival of embryos reared in water and non-water (dry) media until they hatch. The results showed that the embryos reared with dry media hatched one day faster than those raised in water media. The dry-incubated embryo also had an average total length longer than those incubated with embryo rearing media (ERM). In this study, it was concluded that fish embryos of Oryzias celebensis could be transported dry for up to five days.

Developing Inside a Layer of Germs—A Potential Role for Multiciliated Surface Cells in Vertebrate Embryos

This paper reviews current research on the microbial life that surrounds vertebrate embryos. Several clades are believed to develop inside sterile—or near-sterile—embryonic microhabitats, while others thrive within a veritable zoo of microbial life. The occurrence of embryo-associated microbes in some groups, but not others, is an under-appreciated transition (possibly transitions) in vertebrate evolution. A lack of comparable studies makes it currently impossible to correlate embryo-associated microbiomes with other aspects of vertebrate evolution. However, there are embryonic features that should instruct a more targeted survey. This paper concludes with a hypothesis for the role of multiciliated surface cells in amphibian and some fish embryos, which may contribute to managing embryo-associated microbial consortia. These cells are known to exist in some species that harbor in ovo microbes or have relatively porous egg capsules, although most have not been assayed for embryo-associated microbiota. Whether the currents generated within these extraembryonic microhabitats contribute to culturing consistent microbial communities remains to be seen.